Facility management systems are systems which generally monitor and control the environment, energy use, and security of a building. Facility management systems generally include monitoring arrangements, facility control devices, and actuating arrangements.
Monitoring arrangements are arrangements which sense one or more environmental parameters and produce a signal representative of the environmental parameter. Monitoring arrangements generally include at least one sensing device and circuitry to produce a signal representative of the sensed parameter. Typical environmental parameters include temperature and pressure. Common sensing devices include thermostats, flow switches, and HVAC system inputs. The circuitry employed to produce the signal may be an analog to digital converter. A monitoring arrangement may also contain additional circuitry to interface with a control device or network.
Facility control devices are devices which receive the environmental data from the monitoring arrangements, analyze the data, and transmit control data. Facility control devices may also receive direct user input through, for example, a keyboard or control panel. Typical facility control devices include network control units, application specific controllers and operator workstations. Network control units include devices such as programmable control panels. Application specific controllers include devices such as air handling unit controllers, intelligent lighting controllers, unitary equipment controllers, variable air volume box controllers, intelligent access controllers, lab and central plant controllers, and intelligent fire controllers. Operator workstations include devices such as personal computers and network terminals.
Actuating arrangements are arrangements which affect the environment, energy use, or security of a building. Actuating arrangements generally include an actuator, an actuated device, and circuitry to interface between the actuator and a control device or network. An actuator is a mechanism to activate process control equipment by use of electronic signals. An actuated device is any device which affects the environment, energy use, or security of a building. Common actuated devices include fans, air conditioning units, heaters, alarms, and multiplexers to which such devices are connected.
As currently practiced, communication between the various components of a facility management system takes place over a plurality of proprietary network systems. For example, network control units may communicate with each other and with operator workstations through a local area network (LAN), such as ARCNET. LANs generally include proprietary network circuit boards which must be installed in each node (facility control device) of the network, communication lines which connect the various network boards to each other, and software to monitor and regulate the information transfer between the nodes. LANs may also require that specialized hardware, such as two-port or multi-port repeaters, be placed between some or all of the nodes of the network to retransmit messages to the network's nodes and/or provide electrical isolation between nodes. The lines connecting the various nodes of a LAN are typically coax cable, twisted pair, or optical fiber.
The numerous lines required to connect the nodes of a local area network may be configured in star, bus, daisy-chain, ring, tree, and mixed configurations. In a star configuration, all nodes are directly connected to a central node. That is, a separate line runs from every node of the network to the central node of the network without passing through any other node of the network. An advantage of the star network is that upon failure of any node other than the central node, communication is not severed between the remaining nodes. One disadvantage of the star configuration is that if the central node fails, the entire network breaks down and no communication is possible among any of the remaining nodes. A further disadvantage of the star configuration is that the central node becomes a bottleneck to network throughput. That is, the central node must process and route all data transmissions, including all transmissions between any two non-central nodes of the network. For example, for a first non-central node to transmit data to a second non-central node, the first non-central node must transmit the data to the central node. The central node receives the data and evaluates the software data header to determine the desired destination node. When the destination node is determined, the central node retransmits the data to the second non-central node. For a network employing such a configuration, the total amount of inter-node communication is limited to the number of transmissions the central node can process. On large networks, such limitations may be severe.
In a bus configuration, nodes are connected to an electrically continuous section of line that is terminated at both ends. One disadvantage of the bus configuration is that the failure of any node may have the effect of severing communications between the nodes connected to one side of the failed node and the nodes connected to the other side of the failed node. Thus, in networks in which intermediary nodes must regenerate signals, a single node failure will split the original network into two independently operating networks which cannot communicate with each other. While this result is less desirable than that which arises from the failure of a non-central node in a star-configured network, it is preferable to the total communication breakdown that would result upon failure of a central node of a star-configured network. A second disadvantage to a bus-configured network is that the communication between any two nodes must be processed by all intermediary nodes, that is, the nodes between the node sending the transmission and the node to which the transmission is sent. The intermediary nodes must, as a minimum, decipher the software address header of every communication to determine whether it is directed to themselves.
A mixed configuration is simply a combination of the star and bus configurations. For example, many nodes may be connected directly to a central node, while one of the non-central nodes is also connected to a bus-configured second set of nodes. The various subconfigurations of a mixed configuration have the same node-failure problems as their corresponding network configurations, as discussed above.
A second network is often required to provide communication between remote facility control devices, such as application specific controllers, and centralized facility control devices, such as network control units. These secondary networks are employed to avoid the expense of extending the primary network to remote locations where some facility control devices, such as application specific controllers, may be located. The types of data transmitted on such secondary networks include time synchronization messages from primary network facility control devices, commands from primary network facility control devices to secondary network facility control devices, data requests from primary network facility control devices to secondary network facility control devices, and responses from secondary network facility control devices to primary network facility control devices. The secondary network facility control device responses may include data representative of identification, changes of state, advisories, requested data values, or complete data bases. The secondary network may link a plurality of facility control devices to a single primary network facility control device. Thus, if a primary network facility control device fails, communication between the nodes of the primary network and the nodes of the secondary network to which the particular failed device was attached would be severed.
A third network may be employed to connect a plurality of monitoring and actuating arrangements to a secondary network facility control device. Many facility management functions require the use of all the networks of a facility management system. For example, for a user of a tri-network facility management system to access the environmental parameter of a particular monitoring arrangement, a series of data transmissions substantially similar to the following must take place:
A first facility control device located on the primary network receives a user request to display the environmental parameter of the monitoring arrangement through a user input device, such as a keyboard. The first facility control device then transmits data indicative of the user request (control data) over the primary network to a second facility control device linked to a secondary network to which the relevant monitoring arrangement corresponds. During the transmission the control data must be processed by all intermediary nodes of the primary network. PA1 The second facility control device transmits the control data over the secondary network to a third facility control device linked to a tertiary network to which the relevant monitoring arrangement is connected. During this transmission the control data must be processed by all intermediary nodes of the secondary network. PA1 The third facility control device reads the signal generated by the relevant monitoring arrangement over the tertiary network. To accomplish this, the third facility device must be capable of separating the signal generated by the relevant monitoring arrangement from the signals of all other monitoring arrangements on the tertiary network. Upon reading the relevant signal, the third facility control device transmits data indicative of the environmental parameter (environmental data) through any intermediary nodes to the second facility control device over the secondary network. PA1 Finally, the second facility control device transmits the environmental data over the primary network through any intermediary nodes to the first facility control device, where the data is ultimately displayed to the user.
Communication techniques such as polling may be employed to alter the exact sequence of the above series of communications. However, the overall number of communication events required by the single operation described would not decrease.
The implementation of such a plurality of networks is both cumbersome and inherently unreliable. The failure of one node may sever communication between large subnetworks of the system. For example, the failure of a facility control device on the primary network will sever communication between the facility control devices on the secondary network to which the failed facility control device is linked and all other components of the facility management system. Likewise, the failure of a facility control device on the secondary network will sever communication between all other components of the facility management system and the monitoring and actuating arrangements on the tertiary network to which the failed facility control device is connected.
A further difficulty arising from the use of a plurality of proprietary networks is that the nodes which link incompatible networks must be equipped with the particular hardware interface and software intelligence required to connect to and communicate over both networks, that is, the node must be "bilingual." A bilingual node must incorporate a plurality of technologies and protocols and is necessarily more complex than one employing a single network technology. The increased complexity of bilingual nodes results in increased costs of designing, manufacturing, maintaining, and repairing such nodes.
The cost of installing the communication lines required by current network-based facility management systems is formidable. Facility management system users must either incur the imposing expense and inconvenience of installing the plethora of wiring required by such networks within the structure of their building, or suffer the inconvenience and aesthetic degradation created by a multitude of visible cables running from room to room between the various facility management devices. The cost of such networks is exacerbated when the wires must be laid across long distances, such as from a temperature sensor in the basement of a large building to a network control unit on the roof of the building. The cost of laying wires between buildings makes multi-building facility management systems even less feasible, especially when the buildings involved are not closely situated. The transmission of signals over such distances also increases the likelihood that special hardware will be required to boost the signal of the data transmission due to signal degradation.
As currently practiced, facility management systems generally employ a plurality of networks to provide communication between the various components thereof. Referring to FIGS. 1 and 2, examples of current facility management systems are shown. FIG. 1 shows a tri-network facility management system 10 with a bus-configured primary network 12 while FIG. 2 shows and a tri-network facility management system 50 with a star-configured primary network 52. As currently practiced, a primary network may also be configured in a mixed-configuration (not shown).
Tri-network facility management system 10 includes bus-configured primary network 12, a secondary network 18, and a tertiary network 24. Bus-configured primary network 12 includes a plurality of primary network facility control devices 11, 12, 15, and 17 which transmit data between themselves over a plurality of bus-configured network lines 16. Secondary network 18 includes a plurality of secondary network facility control devices 19 and 21, and network facility control device 11, which transmit data between themselves over a plurality of secondary network lines 22. Tertiary network 24 includes facility control device 21, an actuating arrangement 26 and a plurality of monitoring arrangements 28 and 30, which communicate over a plurality of tertiary network lines 25.
While facility management system 10 possesses a single secondary network, network 18, and single tertiary network, network 24, a facility management system may possess any number of secondary and tertiary networks.
When primary network facility control device 17 receives a user request to display an environmental parameter sensed by monitoring arrangement 30, facility control device 17 transmits data indicative of the user request (control data) over primary network lines 16, through facility control devices 15 and 13 to facility control device 11 which is a component of secondary network 18. Facility control device 11 then transmits control data over secondary network lines 22 through facility control device 19 to facility control device 21. Facility control device 21 samples the signal generated over tertiary network lines 25 by monitoring arrangement 30. Facility control device 21 then transmits data indicative of the environmental parameter (environmental data) to facility control device 11 over secondary network lines 22 through facility control device 19. Finally, facility control device 11 transmits the environmental data over primary network lines 16 through facility control devices 13 and 15 to facility control device 17, where the data is ultimately displayed to the user.
Referring to FIG. 2, tri-network facility management system 50 includes star-configured primary network 52, a secondary network 58, and a tertiary network 64. Primary network 52 includes a plurality of primary network facility control devices 66, 68, 70, 72, 74, 76, 78, 80 and 82 which transmit data between themselves over a plurality of network lines 84. Secondary network 58 includes a plurality of secondary network facility control devices 86 and 88, and network facility control device 72, which transmit data between themselves over a plurality of secondary network lines 90. Tertiary network 64 includes facility control device 86, a plurality of actuating arrangements 92 and 94, and a monitoring arrangement 96 which communicate over a plurality of tertiary network lines 98.
While facility management system 50 possesses a single secondary network, network 58, and a single tertiary network, network 64, a facility management system may possess any number of secondary and tertiary networks.
A user request for environmental data is processed by facility management system 50 as described above in reference to facility management system 10. However, facility control device 66 is the only primary network intermediary node that must process the communications between facility control device 72, to which secondary network 58 is linked, and any other primary network node.
Both facility management system 10 and facility management system 50 require the use of bilingual facility control devices to link secondary networks with primary networks, and to link tertiary networks with secondary networks. For example, facility control device 11 and facility control device 72 must incorporate the software and hardware required by both the primary and secondary network to which they belong. Likewise, facility control device 21 and facility control device 86 must incorporate the software and hardware required by both the secondary and tertiary networks to which they belong.
Until recently, telephone companies have been managing two separate networks, a circuit switched network for voice calls and a packet switched network for data calls. Acting upon an idea that originated as early as 1959, telephone companies have now begun to combine the capabilities of both networks into a single digital network called Integrated Digital System Network (ISDN). Currently, there are two defined interfaces to ISDN implemented in the United States, the Basic Rate Interface (BRI) and Primary Rate Interface (PRI). The BRI is the replacement for the normal phone line with the difference that the data is transferred in digital form and the line is divided into three logical channels, two bearer channels (B-channels) and one data channel (D-channel). The B-channels are designed to carry either a voice call or a data call. By using digital signalling, the B-channel has the capability of sending data at 64 kilobytes per second, which is presently about 4 times faster than the,speed at which a conventional modem can communicate over analog telephone lines. The D-channel is designed to perform out-of-band signalling for the B-channels, such as dialing, call setup, and call tear down, and may also be used for low speed data transmission. The speed of the D-channel is 16 kilobytes per second.
ISDN has been discussed in reference to a limited range of facility management applications. For example, the Fujitsu Network Switching Application Profile by Allan Conroy, docket number 830013.0 (Nov. 6, 1990) (Fujitsu Profile) discloses that a central processor may use the ISDN D-channel permanent virtual circuits and the ISDN B-channel packet services to transmit data to, and receive data from, a plurality of control processors. The facility management system thus disclosed is similar to a star-configured network in that the plurality of communication lines run directly from a single node (the central processor) to every other node of the network. The Fujitsu Profile also discloses that a host computer may transmit data to and receive data from such a central processor using the B-channel circuit data services. While the system described in the Fujitsu Profile may avoid the cost of laying lines for a primary network, it does not address the reliability and bottleneck problems inherent in a star configuration, as discussed above. The Fujitsu Profile does not employ a tertiary network, nor does it disclose any change in the wiring or protocol used to connect sensing and actuating arrangements to its control processors. Rather, the article discloses that its processor to actuator/sensor network would not be replaced by ISDN services.
Accordingly, the need exists for a facility management system in which a single node failure will not cause a severence of communication between the remaining nodes. It is further desirable to provide a facility management system that eliminates the communications bottleneck caused by unnecessary communication processing by intermediary nodes. It is further desirable to provide a facility management system in which a single node failure will not cause a severence of communication between two or more networks. It is further desirable to provide a facility management system which employs a network which does not require the user to incur the expense and aesthetic degradation associated with the installation of new wiring. It is further desirable to provide a facility management system which allows inexpensive expansion of the system over long distances. It is further desirable to provide a facility management system which employs a network that does not require the user to employ special signal-boosting hardware when communicating over long distances. It is further desirable to provide a facility management system which does not require the use of complex and expensive bilingual facility control devices.